Herong's Notes on Physics - Version 3.21, by Dr. Herong Yang
Galilean Diagram of Moving Frames
This section presents a single diagram that represents a moving frame overlaid on a stationary frame. The time axis of the moving frame is rotated towards the moving direction.
In previous section, we presented Bob's frame and Amy's frame as separate diagrams. We can also overlay both frames in a single diagram and keep the current location of object O overlapped as a single point:
In the above diagram, coordinates of both frames are maintained as orthogonal coordinate systems. The origin of the Amy's frame in blue color is moving at a speed of v. The Galilean transformation is clearly presented by looking at the difference of distances from object O to t axis and t' axis.
However, world lines of Amy, Bob and object O are presented with different lines for different frames. We can also revise the diagram to simplify those world lines by:
As you can see, now world lines of Amy, Bob and object O are perfectly identical in both frames. The Galilean transformation between two frames is clearly presented in a single simple diagram. Let's call it Galilean diagram.
The only downside of the Galilean diagram is that t' axis is no longer orthogonal to x' and t' has a different scale than t.
To determine the coordinates (X',T') of an event in (x',t') frame, we have to:
Last update: 2014.
Table of Contents